The present invention relates to an airbag provided with a venthole that absorbs an impact by discharging a gas from an inside of an airbag to an outside thereof and a limiting member that limits a discharge of a gas from the venthole, and more specifically, it relates to an airbag constructed in a manner such that the venthole is closed until an object contacts an occupant-facing surface of the expanded airbag, and that the venthole is opened when the object contacts the occupant-facing surface of the expanded airbag and thereby the occupant-facing surface is retreated. Further, the present invention relates to an airbag apparatus provided with the airbag.
Incidentally, in the explanation below, the upper, lower, left, and right correspond to the upper, lower, left, and right for a person who faces an occupant-facing surface of an expanded airbag.
In addition, in the present invention, “object” refers to a human body seated in a seat, a child seat mounted on the seat, a package, or the like.
Hitherto, it is well known that a venthole is provided with an airbag, and a vehicle occupant or the like is softly received by means of the airbag by discharging a gas from the inside of the airbag through the venthole when the vehicle occupant or the like hits the expanded airbag.
Japanese Unexamined Patent Application Publication No. 6-127330 discloses an airbag, which is constructed in a manner such that a venthole is closed until an occupant contacts an occupant-facing surface of the expanded airbag, and that the venthole is opened when the occupant contacts the occupant-facing surface of the expanded airbag and thereby the occupant-facing surface is retreated.
The airbag described in the same publication is configured to have a bag shape by stitching each of peripheral edge portions of an upper base cloth and a lower base cloth having an approximately round shape. In the same publication, the upper base cloth constitutes the occupant-facing surface of the airbag. A gas-flowing inlet where an inflator (gas generator) is inserted is provided at a center of the lower base cloth. A venthole is disposed at a position situated near an outer peripheral side in relation to the gas-flowing inlet of the lower base cloth.
In the same publication above, as illustrated in FIG. 2 thereof, four ventholes are provided in the lower base cloth, and these ventholes are disposed at an upper side, a lower side, a left side, and a right side of the gas-flowing inlet, respectively, to be equally spaced in a peripheral direction of the airbag.
In the lower base cloth, slits are respectively provided in an area between these ventholes and the gas-flowing inlet, and straps are respectively inserted through these slits. One end side of each strap disposed in an inside of the airbag is stitched to an airbag-inside surface of the upper base cloth. Further, the other end side of each of the straps disposed outside the airbag is pulled around an outer peripheral side of the lower base cloth in a manner so as to traverse the venthole nearest to each of the slits, from the slit where each of the straps is inserted, along an airbag-outside surface of the lower base cloth, and is stitched to a position situated near an outer peripheral side of the lower base cloth in relation to each of the ventholes.
The aforementioned one end side of the strap that covers the upper side venthole is stitched to a position in the vicinity of a middle portion between a center portion and an outer peripheral portion of the upper base cloth at an upper side in relation to a center portion of the upper base cloth. The aforementioned one end side of the strap that covers the lower side venthole is stitched to the position in the vicinity of the middle portion between the center portion and the outer peripheral portion of the upper base cloth at a lower side in relation to the center portion of the upper base cloth. The aforementioned one end side of the strap that covers the left side venthole is stitched to the position in the vicinity of the middle portion between the center portion and the outer peripheral portion of the upper base cloth at a left side in relation to the center portion of the upper base cloth. Furthermore, the aforementioned one end side of the strap that covers the right side venthole is stitched to a position in the vicinity of the middle portion between the center portion and the outer peripheral portion of the upper base cloth at a right side in relation to the center portion of the upper base cloth.
In the same publication, when the airbag is expanded, each strap is under tension along with a separating operation of the upper base cloth and the lower base cloth of the airbag. At this moment, the aforementioned other end side of each of the straps is overlapped with each of the ventholes while being tensed along the airbag-outside surface of the lower base cloth, and each of the ventholes is closed. Thereby, a discharge of a gas from each of the ventholes is limited, and the inside of the airbag is rapidly brought to a high pressure state, and the airbag is rapidly expanded.
When the occupant contacts the upper base cloth of the expanded airbag, and the upper base cloth is retreated toward the inside of the airbag, each of the straps is loosened and the aforementioned other end side of each of the straps is spaced apart from each of the ventholes by means of gas pressure in the inside of the airbag. Thereby, each of the ventholes is opened and the gas is discharged from each of the ventholes toward an outside of the airbag. As a result, the occupant is softly received by means of the airbag.
As described above, in the airbag in the aforementioned Japanese Unexamined Patent Application Publication No. 6-127330, the ventholes are respectively provided at the upper side, the lower side, the left side, and the right side of the gas-flowing inlet relative a center of the lower base cloth, and the aforementioned one end side of each of the straps that covers the ventholes is respectively connected to each portion of the upper side, the lower side, the left side, and the right side in relation to the center portion of the upper base cloth.
Consequently, in a state that the airbag is expanded, in a case that the occupant contacts a right end side or a left end side in relation to the center portion of the upper base cloth in a displaced manner, the left side venthole or the right side venthole is opened earlier as compared to a case that the occupant contacts the center portion of the upper base cloth, and there is a possibility that an opening amount thereof is brought to be larger.
It is an object of the present invention to provide an airbag capable of sufficiently discharging a gas from a venthole toward an outside of the airbag when an occupant contacts a center portion, in a left and right direction, of an occupant-facing surface of the expanded airbag, and suppressing the discharge of the gas to the outside of the airbag when the occupant contacts a left end side or a right end side in relation to the center portion, in the left and right direction, of the occupant-facing surface of the expanded airbag, in the airbag constructed in a manner such that the venthole is closed until the occupant contacts the occupant-facing surface of the expanded airbag, and the venthole is opened when the occupant contacts the occupant-facing surface of the expanded airbag and the occupant-facing surface is thereby retreated, and to provide an airbag apparatus provided with the airbag.
Further objects and advantages of the invention will be apparent from the following description of the invention.